Run results for: Bug with Resizing ImageBitmap causes slower than expected performance

There is currently a bug on Chrome Version 74.0.3729.131 (Official Build) (64-bit) (5/12/2019) with ImageBitmap where attempting to resize an ImageBitmap through ImageBitmapOptions will causes the resulting ImageBitmap to render very poorly when used with drawImage, even if the resulting ImageBitmap is resized to be smaller than the source image.

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36

Browser: Chrome 69

Operating system: Windows

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Image	218288.0 Ops/sec
ImageBitmap/Offscreen	228521.5 Ops/sec
ImageBitmap/Offscreen Resized	12614.2 Ops/sec

Script Preparation code:

var img = new Image();
img.decoding = 'sync';

var imageBitmap;
var imageBitmapResized;
var doneLoading = false;
let canvas = document.createElement('canvas');

canvas.width = 640;
canvas.height = 480;
let canvas2 = document.createElement('canvas');
let offscreen = canvas2.transferControlToOffscreen();
offscreen.width = 640;
offscreen.height = 480;

var ctx = canvas.getContext('2d');
var ctx2 = offscreen.getContext('2d');

img.addEventListener('load', function() {
  
  Promise.all([
    createImageBitmap(img)
  ]).then(function(images) {
  imageBitmap = images[0];
  doneLoading = true;
}, false);
  
  Promise.all([
    createImageBitmap(img, {imageOrientation: "none", premultiplyAlpha: "none", resizeWidth:~~(img.width/2), resizeHeight:~~(img.height/2), resizeQuality:"low"})
  ]).then(function(images) {
  imageBitmapResized = images[0];
  doneLoading = true;
}, false);
  
});

img.src = 'https://media.discordapp.net/attachments/447410261289205781/574359442913492992/unknown.png';

Tests:

Image
if (doneLoading) ctx.drawImage(img,0,0);
ImageBitmap/Offscreen
if (doneLoading) ctx.drawImage(imageBitmap,0,0);
ImageBitmap/Offscreen Resized
if (doneLoading) ctx.drawImage(imageBitmapResized,0,0);

Run results for: Bug with Resizing ImageBitmap causes slower than expected performance

Image

ImageBitmap/Offscreen

ImageBitmap/Offscreen Resized